Severe Thunderstorm Warning 429, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
1200 PM CST FRI NOV 23 2001

A BUSY AFTN/EVE BEGINNING TAKING SHAPE...SO WL ISSUE AFD EARLY.

EXPECT SCT TSRA TO DEVELOP LATE THIS AFTERNOON ALONG AND EAST OF THE
HWY 75 CORRIDOR. GIVEN THE MAGNITUDE OF SHEAR AND INSTABILITY
AVAIL...SUPERCELLS ARE A LIKELYHOOD...AND HAVE CONTINUED SVR WORDING
IN THE ZNS. GOOD THERMODYNAMICS AND EXCELLENT KINEMATICS SUGGEST THE
POTENTIAL FOR LARGE TORNADOES LATE THIS AFTERNOON AND THIS EVENING.
BROKEN LINE OF STORMS SHOULD PUSH EAST OF MUCH OF THE CWFA BY
MIDNIGHT OR SHORTLY THEREAFTER. WL CARRY LOWEST POPS IN IN THE
WEST...WITH HIGHEST POPS IN WC/NW AR. WL LET WIND ADVISORY GO WITH
THE AFTERNOON PACKAGE.

AFTER TONIGHT...TOMORROW PROMISES TO BE A STELLAR DAY ACROSS MUCH OF
THE CWFA...WITH THE EXCEPTION OF NRN ZNS...WHERE WRAP AROUND CAA
CLOUDINESS WL KEEP THINGS RATHER CLOUDY FOR MOST OF THE DAY.
AVN/ECMWF/ETA ARE ALL IN EXCELLENT AGREEMENT.

WINDS WL QUICKLY RETURN TO THE S...ALLOWING SOME LIMITED MOISTURE TO
ONCE AGAIN RETURN. ANOTHER STRONG SHORTWAVE PUSHES OUT INTO THE
PLAINS ON MONDAY. ATTM...LOOKS LIKE THE THREAT IS FAIRLY LOW AS MUCH
OF THE FORCING WL BE TO THE N OF THE CWFA...AND WL LEAVE THE POPS
OUT FOR NOW.

MEDIUM RANGE MODELS HAVE FINALLY COME INTO GOOD AGREEMENT THROUGH
THE REMAINDER OF THE FCST. STRONG CDFNT PUSHES THROUGH THE CWFA ON
MONDAY...BRINGING ANOTHER AIRMASS CHANGE. DON/T FEEL THAT THIS ONE
WL BE PARTICULARLY COLD AT THE ONSET AS IT IS PAC IN NATURE. A SMALL
PIECE OF POLAR AIR TRIES TO BREAK OFF AND ROCKET DOWN THE PLAINS ON
WED/THU COOLING TEMPS OFF BUT BRINGING LITTLE IN THE WAY OF ANY
PCPN. THU/FRI SHOULD BE FAIRLY COOL WITH THE POLAR AIR IN PLACE. WL
KEEP LOW POPS ON WEDNESDAY NIGHT...AS THERE ARE HINTS OF LGT
OVERRUNNING PCPN MAINLY ACROSS SRN AND ERN ZNS. OTRW...QUIET WX FOR
THE REMAINDER OF THE XTND.

FORECAST PACKAGE WL BE RELEASED AROUND 400 PM.

MANNING
FCSTID = 24

...PRELIMINARY NUMBERS...
TUL   50  62  38  62 /  40   0   0   0
FSM   54  64  38  65 /  70  10   0   0
MLC   53  64  39  66 /  50  10   0   0
BVO   47  58  36  61 /  40   0   0   0
FYV   49  60  36  60 /  70  10   0   0
BYV   50  59  35  59 /  70  10   0   0
MIO   48  59  36  60 /  60  10   0   0
MKO   52  63  38  64 /  50  10   0   0
F10   52  63  38  64 /  40  10   0   0
HHW   53  65  39  67 /  50  10   0   0

.TSA...
AR...WIND ADVISORY THIS AFTERNOON FOR ZONES
ARZ001>002...ARZ010>011...ARZ019>020...ARZ029.

OK...WIND ADVISORY THIS AFTERNOON FOR ZONES
OKZ049...OKZ053>064...OKZ066>076.

ARZ001-002-010-011-019-020-029-OKZ049-053>076-241200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
100 PM CST FRI NOV 23 2001

...A FEW SEVERE THUNDERSTORMS EXPECTED THIS AFTERNOON AND EVENING...

THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF AN EASTWARD
MOVING DRYLINE THIS AFTERNOON AND THIS EVENING.  A FEW OF THE STORMS
ARE EXPECTED TO BE SEVERE...MAINLY OVER EASTERN OKLAHOMA TO THE EAST
OF HIGHWAY 75 AFTER 3 PM...THEN ACROSS NORTHWEST ARKANSAS BY EARLY
THIS EVENING.

THUNDERSTORMS CAPABLE OF PRODUCING LARGE HAIL...DAMAGING WINDS AND
TORNADOES WILL BE POSSIBLE.  THE SEVERE WEATHER THREAT WILL DIMINISH
BY LATE THIS EVENING AS THE AIRMASS STABILIZES AND THE WEATHER
SYSTEM RESPONSIBLE FOR THE STORMY WEATHER MOVES TO THE NORTHEAST OF
THE AREA.

.SPOTTER ACTIVATION...
SPOTTER ACTIVATION WILL LIKELY BE NEEDED FOR PARTS OF EASTERN
OKLAHOMA LATER THIS AFTERNOON...AND FOR NORTHWEST ARKANSAS BY LATE
THIS AFTERNOON OR EARLY THIS EVENING.

.DISCUSSION...
SURFACE LOW PRESSURE OVER CENTRAL KANSAS EARLY THIS AFTERNOON WILL
CONTINUE TO MOVE TO THE NORTHEAST THROUGH THE EVENING AND INTO
SOUTHERN IOWA BY SATURDAY MORNING.  THE SURFACE DRYLINE EXTENDED
SOUTH FROM THE SURFACE LOW INTO CENTRAL OKLAHOMA EARLY THIS
AFTERNOON AND WILL CONTINUE TO MOVE TO THE EAST.  A 100 KNOT UPPER
JET WILL SPREAD ACROSS WEST TEXAS AND INTO SOUTHEAST OKLAHOMA THIS
AFTERNOON AND EVENING...WHILE A 40 TO 50 KNOT LOW LEVEL JET HAS
BECOME ESTABLISHED FROM EASTERN TEXAS INTO EASTERN OKLAHOMA AND
WESTERN ARKANSAS.

SCATTERED THUNDERSTORMS ARE FORECAST TO DEVELOP ALONG AND AHEAD OF
THE DRYLINE DURING THE AFTERNOON AS CONVECTIVE ENERGY VALUES RISE TO
VALUES RANGING FROM 1500 TO 2000 J/KG.  LIFTED INSTABILITIES WILL
REACH VALUES AROUND -4.  VERTICAL WIND SHEAR WILL BE FAVORABLE FOR
SEVERE THUNDERSTORMS AND SUPERCELLS...ESPECIALLY ACROSS NORTHEAST
OKLAHOMA EAST OF HIGHWAY 75...THEN DEVELOPING INTO NORTHWEST ARKANSAS
BY EARLY THIS EVENING.  SUPERCELL THUNDERSTORMS WITH TORNADIC
POTENTIAL WILL BE MOST LIKELY WITH INITIAL STORM DEVELOPMENT THIS
AFTERNOON...THEN THE STORMS ARE EXPECTED TO EVENTUALLY FORM INTO A
SQUALL LINE.  THE SQUALL LINE WILL THEN SWEEP QUICKLY TO THE EAST
WITH LARGE HAIL AND DAMAGING WINDS THE PRIMARY THREAT.

THREAT TABLE
VALID THROUGH 1200 UTC SATURDAY

AREA 1...ALONG AND EAST OF HIGHWAY 75
THUNDERSTORM PROBABILITY...70
SEVERE PROBABILITY IF STORMS OCCUR...70
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...50

AREA 2...WEST OF HIGHWAY 75
THUNDERSTORM PROBABILITY...40
SEVERE PROBABILITY IF STORMS OCCUR...40
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...20

THREAT AREAS DEFINE THE GREATEST RISK. PROBABILITIES ARE IN PERCENT.
SIGNIFICANT SEVERE IS DEFINED AS F1 OR GREATER WIND/TORNADO DAMAGE
AND/OR GOLFBALL SIZE HAIL OR LARGER.

RELATED GRAPHICAL INFORMATION CAN BE FOUND AT...
WWW.SRH.NOAA.GOV/TULSA/HWO.HTML

NNNN

ARZ001-002-010-011-019-020-029-OKZ049-053>076-241200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
535 PM CST FRI NOV 23 2001

...UPDATE...

AN OUTBREAK OF SEVERE THUNDERSTORMS IS STILL EXPECTED ACROSS FAR
EASTERN OKLAHOMA AND NORTHWEST ARKANSAS THIS EVENING AND TONIGHT.

A POWERFUL STORM SYSTEM WAS MOVING SLOWLY ACROSS THE CENTRAL
PLAINS.  THIS SYSTEM SLOWED ITS PROGRESS TODAY AS IT CONTINUED TO
STRENGTHEN.  HOWEVER IT WILL ACCELERATE EAST TONIGHT AS STRONG
JET STREAM WINDS PUNCH INTO THE CENTRAL U.S.

SCATTERED THUNDERSTORMS WILL DEVELOP IN EASTERN OKLAHOMA AND
EXTREME WESTERN ARKANSAS BETWEEN 6PM AND 8PM AND QUICKLY BECOME
SEVERE. THE STORMS WILL FORM A LINE AND RACE ACROSS NORTHWEST
ARKANSAS...WITH THE THREAT DIMINISHING AFTER 2AM AS THE LINE EXITS
THE AREA.

VERY STRONG WIND FIELDS AND INCREASING INSTABILITY WILL PROMOTE STORM
ROTATION AND SUPERCELLS. THERE WILL BE A THREAT FOR TORNADOES AND
VERY LARGE HAIL FOR THE FIRST SEVERAL HOURS OF THE EVENT...WITH THE
THREAT TRANSITIONING TO DAMAGING WINDS AS THE STORMS FORM INTO A
LINE.

GIVEN THE FAST WINDS ALOFT THERE IS THE POTENTIAL FOR
STRUCTURAL DAMAGE IN THE MOST SEVERE STORMS.  PERSONS IN EASTERN
OKLAHOMA AND NORTHWEST ARKANSAS SHOULD PAY CLOSE ATTENTION TO THE
WEATHER TONIGHT AND BE READY TO ACT.

STAY TUNED TO THIS STATION FOR FURTHER INFORMATION FROM THE NATIONAL
WEATHER SERVICE.